Chernobyl
experienced the worst nuclear
power plant disaster in history 24 years ago. Now with the
use of DNA sequences, scientists studying different species in this
area have been able to determine which
are more vulnerable and more likely to be damaged by
radiation at this level.

The
Chernobyl disaster occurred on April 26, 1986 when reactor number
four ruptured and exploded due to rapid growths of power output.
Radiation has contaminated the area ever since, dubbing this part of
Chernobyl the "zone of alienation."

Through
the use of DNA
sequences, scientists have been able to figure out which
populations of birds, mammals and insects, who live in the zone of
alienation, have been affected the most. DNA is a key factor in
determining this because a species' DNA changes from generation to
generation due to a "natural balance" between mutations and
an individual's ability to fix damaged DNA. This is what allows
species to evolve, and by looking at the substitution rate (the rate
at which the DNA code is replaced by another), scientists are able to
observe DNA sequences and predict which species have been affected
the most (they can also determine if they will decline or become
extinct).

"This
information is available in large database," said Mousseau. "So
you can get the DNA sequences [of each species] and examine the
changes that have occurred among a species over time.

"What
we have discovered is that when we look at the species in Chernobyl,
we can predict, based on their substitution rates, which ones are
most vulnerable to contaminants."

According
to the results of this study, brightly colored birds and birds who
travel long distances to migrate are the most vulnerable to
radioactive contamination. A reason for this, according to Mousseau,
could be that these birds have weaker DNA repair mechanisms.

Evolutionary
Biologist Louise Johnson from the University of Reading noted that
these results were "fascinating" and that it has potential
to test certain predictions about evolution.

"One
of the difficulties of such research is that it isn't really an
experiment - it is impossible to control for all of the confounding
variables," said Johnson. "But [the scientists] have been
very careful to test all of the other factors that could be important
- antioxidants,
population size, body size, etc. of bird species and it
appears...that there is a shared casual relationship between
accumulating mutations over time and the ability to withstand
radiation."